Many types of containers are leak tested by filling the container with a tracer gas and then checking to see if any of the tracer gas is leaking therefrom. To do this, test fixtures are usually required to facilitate the filling of the container with the tracer gas. Once filled, the environment about the container is sampled for leakage of the tracer gas.
A leak test adapter is disclosed in U.S. Pat. No. 5,548,992. Specifically, an adapter body is attached to a container's test port. A stem having a hex end passes through the adapter body and is pressed into a hex socket of a penetration plug filled with a vacuum grease. To fill the container with tracer gas, the stem is pulled away from the container so that the penetration plug is extracted from the test port thereby defining a flow passage through the test port. Once the container is filled, the stem is pushed towards the container to set the penetration plug in the test port. To secure the plug in the test port, the stem is turned to screw the penetration plug into the test port. With the adapter body still in place, the stem is pulled away from the plug as the vacuum grease releases its hold on the hex end of the stem. The adapter body is then removed and a gas detector is used to sample the environment around the container to check for leaking tracer gas.
This adapter has several drawbacks. Since the penetration plug must be withdrawn from the test port to fill the container, the plug is susceptible to being inadvertently pushed back into the test port as tracer gas is forced thereby. Further, since the penetration plug is only attached to the plug by vacuum grease, the plug could fall off the hex end of the stem thereby requiring complete disassembly of the leak test adapter to reposition the plug. Also, since the vacuum grease does not provide a secure coupling, the plug cannot be well-sealed in the test port using, for example, an o-ring. If an o-ring seal were used, the substantial force required to unseat the plug could cause the hex end of the stem to release from the vacuum grease thereby complicating plug removal. Finally, the use of vacuum grease can be messy.